Process for producing borax and sodium bicarbonate from lake brines



Patented Feb. 16, 1926.

' UNITED STATES, PATENT OFFICE.

' MORRIS V. LOWBY, OF SANTA MARIA, CALIFORNIA, ASSIGNOB TO WEST END CHEMI- CAL COMPANY OF OAKLAND, CALIFORNIA, A CORPORATION OF CALIFORNIA.

PROCESS FOR PRODUCING BOBAX AND SODIUM BICARBONATE FROM LAKE BRINES.

no Drawing Application filed April 10,

To all whom it may concern:

Be it-knovgn that ,I,..MORRIS V. LowRY, a citizen of the United States, and a resident of Santa Maria, county of Santa Barbara,

State of California, have invented a new and useful Process for Producing Borax and Sodium Bicarbonate from Lake Brines,

- of which the followingis a specification.

The. present-invention relates to an improved method of producing borax and sodium bicarbonate from saline lake brines containing sodium borates, sodium. carbonate, sodium chloride, potassium chloride, sodium sulfate and other ingredients. The

1 brine in Searles Lake, San Bernardino County, California, is of suitable character for this process. The following analysis is of brine taken from this: lake:

, Per cent.

20. Borax (Na,B O,10H O) 3.00-

Sodium carbonate (Na CO 5.21;: Sodium chloride (NaCl) 15.92 ,Potassium chloride (KCl) 4:78 Sodium sulfate (Na SQ,) 6.75

M The preferred method'in which my process may be carried out maybe-described as follows: The brine of approximately the above composition is pumped from the lake to, a solar pond and there evaporated to a point where the carbonate content is sufiiciently high to holdjrom 6% to 7% borax in solution at relatively low temperatures During evaporation, sodium chloride, sodium sulfateand possibly potassium chloride or sulfate will crystallize. The evaporated brine will have a composition of which the following analysis is typical:

- J Per cent. 0 Borax (Na,B,O.,10H,O) 5.90 Sodium carbonate lNa CO 10.95 Sodium chloride aCl 12.26

' Potassium chloride (K I; 6.52 Sodium sulfate (Na SO, 4.24

454 The next step is the introduction ofcarbonic acid gas into this brine by any suitable and eificient means and in a proper container. The brinetemp'erature shou d be from 30 to 35 C. The heat generated by the reaction 60 willr'aise the temperature to about 40 C. which is uite permisible for good results. Sodium bicarbonate will be precipitated as the treatment with carbonic acid gas pro- 1923. Serial no. 631,216.

Na CO plus CO plus H O equals 2NaHCO A fairly large proportion of the sodium borates in the brine before carbonation exlst as sodium metaborate. The decrease in the normal sodium carbonate concentration, and the increase of sodium bicarbonate to point of precipitation disturbthe borate equillbrium so that at the finish of carbona- .'tion the borate co'ntent is practically all in form of so dium-tetraborate the less soluble sod um borate; The following reaction exemphfies this point.

2Na l3 O plus H O plus 200 equals .d Na B,O, plus 2NaHCO an 2Na B O plus 2NaHCO equals Na B,O, plus Na oo, plus H O.

The brlne will now he transferred to a suitable tank where it may be cooled by artificial or natural agencies to a temperature Where the solubilities of sodium tetraborate and sodium bicarbonate are comparatively low. Crystal borax and sodium bicarbonate will be recipitated as a sludge at the bottom of t e tank. In addition'to these salts,

which constitute the main portion, the

sludge will contain small amounts of impurlties due to the adherin brine. The

sludge may now be recovere b decanting the clear supernatant liquor or y filtration of the salts from the liquor.

The sludge or filtered salts will now be mixed with water and with raw or calcined colemanite (in either case reduced to a sufficient fineness to promote a rapid and eificient reaction) in a suitable tank and in, proper proportions and heated to a tempera". ture of about C. The borax in the sludge or'filtered salt is thereupon diss0lved.' An exchange takes place between the sodium bicarbonate of the sludge or filtered salt and the colemanite as the following reaction illustrates (iNaHCO plus2Ca B O equals 3Na B O plus4=CaC() plus2CO plusH O.

Thus, part of'the CO in the sodium bicarbonate combines with the CaO in the colemanite to form insoluble calcium carbonate and the B 0 in the eolelnanite combines Thus the total B 0 content of the sludge .from the waste solids.

and colemanite is rendered soluble, less a small amount due to incomplete reaction.

The rich borax liquor will then be filtered Borax will be crystallized from this solution and recovered by a suitable means of separation.

By this process the borax, which was mechanically mixed with the sodium bicarbonate in the sludge, is refined since the sodium,

bicarbonate reacts with the colemanite and theB O content of the refined and recovered borax equals the sum of B 0 content present in the sludge, and the B 0 content which was present in the colemanite. Thus the two crude products are mutually refining toward each other.

bonate, capable of being refined in the usual manner into a high grade product. The second stage of this variation then, upon dropping the temperature, produces a sludge higher in B O and lower in sodium bicarbonate than is the case when only one sludge separation is made, and in this variation the amount of colemanite required for separating the sodium bicarbonate from the borax is less in proportion.

Various other changes and modifications may be made Within the scope of the claim hereto attached without departing from the spirit of the invention.

I claim:

Theprocess of producing crystal borax which consists in concentrating a brine by evaporation, in carbonating the concentrated brine, in cooling the mixture whereby crystal borax' and sodium bicarbonate are precipitated as a sludge, in mixing the sludge with colemanite' and heating the same to substantially boiling temperature.

MORRIS V. LOWRY. 

